The trim around the top edge is a heavy crocheted lace. I linked to a post where I’ve taken close-up images of it, and if you click on the images it links to larger photos of the lace, where you can see the shell pattern on the edge of the lace.

The shoulder straps are a vintage chemise from my collection – it has a lace yolk, and then a fine cotton body.

It’s really beautiful.
Is this a straight fronted/s-bend figure corset? If so, I’m interested if it really affects your posture? It doesn’t seem to, in the pictures. Does it make your back hurt? At least in all the books they say that the straight fronted corsets were really bad for your back.